I don't know how you got a job without a master honestly. Teach me your secrets please. :-)
Do you really think you want to go through an intensive course like medicine again, especially if you have to start from the beginning? If you have the money I guess it's ok. But you can also go in the direction of medicine with food science developing pill shells and so on. And the regulation in the medical industry is unreal from what I heard from people who chose that field.
I also thought about going to study medicine as well, but I would be pretty old when I finish and I don't see the additional benefits from the job (doctors aren't the happiest in general if you know what I'm saying), especially if you already have a degree.
If it is worth the huge extra effort and cost to you then do it, a master might bring more rewards now but if you anyway want to change industries then why not. You can also use the time now to read about the different parts of the food and medicine industries or start learning something different like a language or python or something. I would say that could make you feel better.